Dev Site loading extremely slow

[windsurfer]

For the past few months I have been working and modifying V1.5 and finally uploaded to a dev to test my site only to find that any page loads fast but then something is still loading and it takes approx. 6 seconds for the page to fully load, this causes additional images to display in full page rather then the zen lightbox as can be seen here. http://dev.mysurplus.ca/index.php?ma...products_id=20
If one clicks on the main image right after the page loads it will display full page, if you wait about 5 seconds and the click on the main image it will display properly in the zen lightbox so obviously something is very slow loading. I figured it would be some add on that I installed so I created another subdomain and installed a fresh copy of the latest V1.5 and lo and behold it acts the same way. As seen here http://dev.nostik.ca/ the speed test also reveals that it takes about 6 seconds to load. I have 2 websites on the same server that load in under 1 second with a lot more content so it is not my server.
I also have the same zen sites on my local and they load just fine without delay.
Would somebody have an answer to this please ?.
Thank you.